Injection moulding device and a method of opening and closing a partible mould in an injection moulding device

ABSTRACT

A device for forming injection moulded plastic articles comprises a partible mould ( 5, 7 ) having an inner mould tool ( 5 ) and two outer mould tools ( 7 ). The device further comprises a rotatable hub (4) which supports the inner mould tool ( 5 ). The inner mould tool ( 5 ) is arranged to be moved by the hub ( 4 ) in an essentially circular movement into and out of a mould cavity enclosed by the outer mould tools ( 7 ). Means ( 9 ) for opening and closing the outer mould tools ( 7 ) are arranged to move the outer mould tools ( 7 ) in a first, radial direction (R) and a second, perpendicular direction (P), moving the outer mould tools ( 7 ) so that their central axes (C) coincide throughout the movement. A method of opening and closing a partible mould in an injection moulding device is also disclosed.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a device for forming injection mouldedplastic articles, comprising a partible mould having an inner mould tooland two outer mould tools, the outer mould tools each having a centralaxis, the device further comprising a rotatable hub, the inner mouldtool being supported by the hub, which is arranged to move the innermould tool in an essentially circular movement into and out of a mouldcavity enclosed by the outer mould tools, and means for opening andclosing the outer mould tools around the inner mould tool.

The invention also relates to a method of opening and closing a partiblemould in an injection moulding device, the mould comprising an innermould tool and two outer mould tools, each outer mould tool having acentral axis, the device further comprising a rotatable hub, the innermould tool being supported by the hub.

BACKGROUND ART

Devices and methods of the above-mentioned kind are known (see e.g.EP-A-862 980) wherein a rotatable mandrel wheel has an inner mould toolarranged at the outer end of each mandrel and wherein an outer mouldtool consisting of two outer mould halves is arranged so that the innermould tools through rotation of the mandrel wheel can be successivelymoved into and out of the outer mould tool. Each of the outer mouldhalves is arranged on a pivotable lever which is articulately attachedto a part of the support of the injection moulding device and fixedlyattached to the outer mould half. In order to open the outer mould tool,the outer mould halves are moved sideways away from the inner mould toolby pivoting the pivotable arms. During the opening movement the outermould halves are tilted in relation to each other and to their closedposition. Devices of this type are used, e.g. for injection mouldingplastic tops onto paper sleeves for forming containers. A paper orcarton sleeve is placed on one of the mandrels, the mandrel with thesleeve and the inner mould tool is rotated into the outer mould tool.The outer mould tools are closed around the inner mould tool and the endof the sleeve, and a plastic top is moulded onto the end of the sleeve.A problem with this kind of injection moulding device is that it onlyallows moulding of relatively short or flat plastic tops on the end ofthe sleeve, since the outer mould halves cannot be moved sufficientlyquickly out of the way during opening for allowing the mandrel to passwith a longer or higher plastic part on the end of the sleeve. Anotherproblem is that it may be difficult to align the outer mould halves whenclosing the outer mould tool.

SUMMARY OF THE INVENTION

The object of the invention is therefore to provide a device for forminginjection moulded plastic articles of essentially the same type as theknown device described above, but which allows forming of higher orlonger plastic articles.

Another object is to provide a device for forming injection mouldedarticles allowing improved alignment of the outer mould tools.

Yet another object is to provide a method of opening and closing apartible mould in an injection moulding device, which is quicker thanthe known methods.

Still another object of the present invention is to provide a method ofopening and closing a partible mould which allows higher or longermoulded plastic articles to pass the outer mould tool.

The above-mentioned objects are achieved through a device having thefeatures of appended claim 1, preferred embodiments being defined inclaims 2-15. These objects are also achieved by a method according toappended claim 16, variants thereof being defined by dependent claims17-21.

Thus, in the device of the invention, the means for opening and closingthe outer mould tools are arranged to move the outer mould tools in afirst direction which is radial in relation to the hub and a seconddirection which is perpendicular to the first direction and directed inthe plane of the circular movement of the inner mould tool, moving theouter mould tools so that their central axes coincide throughout themovement. In this manner, the outer mould tools may quickly be openedand moved away from the inner tools, so that the inner mould tool with amoulded plastic article may pass out of the outer mould tool.

In one embodiment, the means for opening and closing the outer mouldtools are arranged to move the outer mould tools in the first and seconddirections at least partly simultaneously. If each outer mould tool ismoved simultaneously in the first and second directions, the opening andclosing movements may be speeded up and the means used for opening andclosing the outer mould tools may be of a simple construction.

In a specific embodiment, the means for opening and closing the outermould tools are arranged to move the outer mould tools along circulararcs. This is an effective way of opening and closing the outer mouldtools, since they are moved simultaneously in the first and seconddirections.

The means for opening and closing the outer mould tools may comprisepivotable levers, each lever being articulately attached at one end toan outer mould tool and at the other end to a mounting part of a supportfor the device. This provides a mechanically simple and reliable meansfor opening and closing the outer mould tools.

The position of the mounting part is preferably fixed. This improves theaccuracy of the control of the movement of the outer mould tools.

The pivoting movement of the pivotable levers may be driven by beltdrive means. Thus, the movement of the pivotable levers can be reliablycontrolled and easily performed.

In one embodiment of the invention, the means for opening and closingthe outer mould tools comprise plane guide means for guiding the outermould tools such that they are aligned when closed. In this way a properalignment of the outer mould tools can be ensured, which promotes acorrect injection moulding process.

The plane guide means may comprise bars on which holders holding theouter mould tools are guided in the second direction. The outer mouldtools can thereby easily and reliably be guided in the second direction.

It is preferred that the plane guide means are movable in relation tothe mounting part. This makes it easier to guide the outer mould toolsin the first direction.

In one embodiment, the belt drive means are parallel with the planeguide means. This allows a simple construction of the device.

In an alternative embodiment, the plane guide means comprise pairs ofparallel pivotable levers, each lever being articulately attached at oneend to an outer mould tool and at the other end to a mounting part of asupport for the device. This provides another mechanically simple, yetreliable way of guiding the outer mould tools.

The device of the invention further preferably comprises radial guidemeans for guiding the outer mould tools in the first direction. Hereby,the desired movement of the outer mould tools may easily be achieved.

The radial guide means may be arranged to guide the plane guide means inthe first direction and thereby guide the outer mould tools in the firstdirection. This is a simple and reliable way of ensuring the movement ofthe outer mould tools in the first direction.

In one embodiment, the radial guide means comprise bars on which theplane guide means are guided. This provides a mechanically simple meansfor guiding the plane guide means.

The device of the invention may further comprise supply means forsupplying a plastic material to be injected, the supply means beingmovable in the first direction with the outer mould tools. In thismanner, the position of the supply means in relation to the mould toolmay be accurately controlled.

The inventive device further preferably comprises a pressure system forpressurizing the injected plastic material, the pressure systemadditionally being arranged as an auxiliary means for closing the outermould tools. This is an efficient way of ensuring the movement of theouter mould tools with a minimum number of components.

In one embodiment, the radial guide means are additionally arranged toguide the supply means. In this manner, the movement of the supply meansand the outer mould tools may easily be synchronized.

According to the invention, the device may further comprise means fordisengaging the outer mould tools from a frame of the device. Thus, itis possible to disconnect the outer mould tools from the frame in aforce sense. As a result, pressure exerted on the outer mould toolsduring injection of plastic material need not be transmitted to theframe.

In the method of the invention, the outer mould tools are moved in afirst direction which is radial in relation to the hub and a seconddirection which is perpendicular to the first direction and directed inthe plane of the circular movement of the inner mould tool, and theouter mould tools are moved so that their central axes coincidethroughout the movement. This method ensures that the outer mould toolsare opened and closed quickly. It further ensures proper alignment ofthe outer mould tools when closed.

The outer mould tools are preferably moved in the first and seconddirections at least partly simultaneously. This makes it possible tospeed up the opening and closing of the outer mould tools.

In a preferred variant of the method of the invention, the outer mouldtools are moved along circular arcs. In this way the movement in thefirst and second directions coincide in time, allowing a particularlyquick opening and closing of the outer mould tools.

In a variant of the method according to the invention, the outer mouldtools are guided on plane guide means in the second direction such thatthey are aligned when closed. This ensures correctly closed outer mouldtools for injection moulding.

The plane guide means are preferably guided on radial guide means in thefirst direction, whereby the outer mould tools are guided in the firstdirection. This is an efficient and simple way of guiding the outermould tools in the first direction.

A supply means for supplying a plastic material to be injected into thepartible mould may be moved in the first direction with the outer mouldtools. In this way the position of the supply means in relation to themould tools may be controlled more easily.

In a preferred variant of the inventive method, the outer mould toolsare disengaged from a frame of the injection moulding device duringinjection of the plastic material. Thus, forces exerted on the outermould tools during injection of plastic material are not transmitted tothe frame.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in more detail with reference to theappended schematic drawings, which show an example of a currentlypreferred embodiment of the invention.

FIG. 1 is a perspective view of a machine for injection moulding plasticarticles onto the end of sleeves forming containers, including a deviceaccording to the invention for forming injection moulded plasticarticles.

FIG. 2 is a perspective view of the two mandrel wheels of FIG. 1.

FIG. 3 is a perspective view of a pair of holders for outer mould toolsin the device of FIG. 1.

FIG. 4 is a perspective view of two sets of pivotable levers for movingthe holders of FIG. 3.

FIG. 5 is a perspective view of belt drive means for driving themovement of the pivotable levers of FIG. 4.

FIG. 6 is a perspective view of an assembly of the holders of FIG. 3,the pivotable levers of FIG. 4 and the belt drive means of FIG. 5.

FIG. 7 is a perspective view of supply means for supplying plasticmaterial for injection in the device of FIG. 1 and guide means for thesupply means and the outer mould tools.

FIG. 8 is a perspective view of an assembly of the parts in FIG. 6 andFIG. 7.

FIG. 9 is a perspective view of the holders of FIG. 3 on mould-lockingbars in an open position.

FIG. 10 is a perspective view of the holders and mould-locking bars ofFIG. 9 in a closed position.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

In FIG. 1, an injection moulding machine 1 is shown. Two mandrel wheels2 can be seen in the top right part of the machine 1.

FIG. 2 shows the two mandrel wheels 2, each having four arms or mandrels3 extending from a central hub 4. At the radially outer end of eachmandrel 3 an inner mould 5 tool is formed. An outer mould tool 5 isclosed around one of the inner mould tools 5 on each mandrel wheel 2.Each outer mould tool 6 is made up of two outer mould tools or mouldtool halves 7, which can be moved apart and towards each other, thusopening and closing around the inner mould tool 5. The mandrel wheel 2is rotatable through positions I, II, III and IV. Each outer mould toolhalf 7 has a central axis C which extends in the tangential direction ofthe rotation of the mandrel wheel 2.

In FIG. 3, a pair of holders 8 for holding the outer mould tool halves 7are shown.

FIG. 4 shows two sets of pivotable levers 9. At one end 10, each lever 9has a projecting pin 11 for articulate connection to the holder 8 inFIG. 3 by means of a hole 12. At the other end 13, the lever isarticulately attached to a fixed mounting part 14 of the support of themachine 1.

In FIG. 5, guide means (referred to as plane guide means as will beexplained below) in the form of horizontal bars 15 for guiding the outermould tools 7 in the second direction (indicated by arrow P in FIG. 2)can be seen. In the machine 1, the holders 8 of FIG. 3 are attached tothe bars 15 by means of holes 16 through which the bars 15 are passed.Further in FIG. 5, belt drive means 17 can be seen, each consisting of acontinuous belt 18 driven via two drive shafts 19 connected to a motor(not shown in FIG. 5) which is held in the motor support 20. Thearrangement of the bars 15 and drive means 17 is supported on a frame 21consisting of two yokes 22.

FIG. 7 shows a pair of supply means 23 for supplying plastic material tobe injected into the mould formed by the inner mould tool 5 and theouter mould tool 6. Three pairs of vertical bars 24 constitute guidemeans (referred to as radial guide means as will be explained below) forguiding the outer mould tool halves 7 and the supply means 23 in thefirst direction (indicated by arrow R in FIG. 2).

The vertical bars 24 guide the outer mould tool halves 7 in the radialdirection R of the mandrel wheel 2 and, for the convenience of thediscussion, are therefore referred to as radial guide means. In the sameway, the horizontal bars 15 guide the outer mould tool halves 7 in thesecond direction P which is perpendicular to the first, radial directionR and directed in the plane of the circular movement of the mandrels 3,and they are therefore referred to as plane guide means. Thedesignations “radial” and “plane” are in no way intended to limit thepossible embodiments of the guide means 15, 24.

A hydraulic cylinder 25 is associated with each supply means 23.

The operation of the machine 1 with its inventive device for forminginjection moulded plastic articles will now be described. On eachmandrel wheel 2, a paper or carton sleeve (not shown) is placed on oneof the mandrels 3 in position I. The mandrel wheel 2 is rotatedclockwise, so that the mandrel 3 with the inner mould tool 5 and thesleeve is brought to position II. During the movement of the mandrel 3into position II, the outer mould tool 6 is open, i.e. the outer mouldtool halves 7 are at a distance from each other. When the inner mouldtool 5 is in position II, the outer mould tool 6 is closed around theinner mould tool 5, thus creating a mould cavity between the inner andouter mould tools 5, 6. The closing of the outer mould tool 6 isaccomplished by means of the pivotable levers 9, which are articulatelyattached to the holders 8 holding the outer mould tool halves 7 and tothe mounting part 14.

With reference to FIG. 6, the movement of the pivotable levers iscontrolled and driven by means of the belt drive means 17. A lower block26 is attached to the lower part of the continuous belt 18 and isconnected to the left-hand pivotable lever 9 a. An upper block 27 isattached to the upper part of the continuous belt 18 and is connected tothe right-hand pivotable lever 9 b. The continuous belt 18 is driven viathe two drive shafts 19.

In FIG. 6, the holders 8 are shown in the position where the outer mouldtool is closed. If the continuous belt 18 in the foreground of FIG. 6 isdriven in the clockwise direction, the blocks 26, 27 are moved away fromeach other and the levers 9 a, 9 b are pivoted such that their upperends 13 are moved outwards, away from each other. Consequently, theholders 8 holding the outer mould tool halves are moved away from eachother. By virtue of the articulate attachment of the levers 9 to theholders 8, the holders 8, and thus the outer mould tool halves 7, may bemoved away from each other without rotating in relation to each other.Thereby, the central axes C of the outer mould tool halves 7, which, asshown in FIG. 2, coincide when the outer mould tool 6 is closed are keptcoinciding throughout the movement. As the holders 8 are moved apartthey slide on the horizontal bars 15. In this manner they are kept inalignment. The pivoting movement of the levers 9 move the holders 8outwards in the horizontal direction P as well as downwards in thevertical direction R. The position of the mounting part 14 is fixed, andtherefore the horizontal bars 15 are movable in the vertical directionR. As the pivoting movement of the levers 9 move the holders 8 outwards,the horizontal bars 15 are forced downwards. In each of the yokes 22,there are two parallel, vertical channels 28 through which, as may beseen in FIG. 8, the vertical bars 24 pass. Thus, as the pivotingmovement of the levers 9 move the holders 8 apart, the yokes 22 slidedownwards along the vertical bars 24, moving the horizontal bars 15, theholders 8 and the outer mould tool halves 7 downwards in the verticaldirection R. During the movement, the supply means 23 are moveddownwards with the yokes 22, the horizontal bars 15, the holders 8 andthe outer mould tool halves 7.

When the outer mould tool 6 is to be closed, the continuous belt 18 isrotated a distance in the counter clockwise direction. The blocks 26, 27urge the upper ends 10 of the levers 9 towards each other. Thus, theholders 8 are moved towards each other, sliding on the horizontal bars15, the holders 8 and outer mould tool halves 7 being held with theircentral axes C coinciding throughout the movement. While the holders 8slide towards each other during the pivoting movement of the levers 9,the yokes 22 holding the horizontal bars 15, holders 8 and outer mouldtool halves 7 slide upwards along the vertical bars. Thus, the outermould tool halves 7 are brought together in correct alignment,eventually forming a mould cavity with the inner mould tool 5.

The hydraulic cylinder 25 of the supply means 23 is used forpressurizing the plastic material to be injected into the mould formedby the inner mould tool 5 and outer mould tool 6. The hydraulic cylinder25 also forms part of an auxiliary system for assisting in the closingof the outer mould tool 6. When the outer mould tool 6 is fully open,the holders 8 are as far apart as possible on the horizontal bars 15,and the yokes 22 are in their lowest position on the vertical bars 24.Thus, in order to close the outer mould tool 6, the frictional forcesacting along the vertical bars 24 and the horizontal bars 15 have to beovercome as well as the gravitational force acting on the entirearrangement. Therefore, the hydraulic cylinders 25 associated with theplastics supply means 23 are used for assisting the motor in moving theyokes 22 upwards along the vertical bars 24 and the holders 8 inwardsalong the horizontal bars 15. Since the pressure normally used forpressurizing the plastic material to be injected is much higher (on theorder of 100 bar) than the pressure needed to move the mould toolarrangement (on the order of 10 bar), the cylinders 25 are driven notvia the normal pressurizing system when working as an auxiliary meansfor opening and closing the outer mould tool 6, but via a pressureaccumulator (not shown). The accumulator is divided by a membrane intoan upper and a lower compartment. The upper compartment is filled withgas and the lower compartment is filled with hydraulic oil and connectedto the hydraulic cylinder 25. As the mould tool arrangement is moveddownwards during opening of the outer mould tool halves 7, the piston ofthe cylinder 25 is moved downwards and oil is pushed into theaccumulator, thus pressurizing the gas in the upper compartment. Forclosing the outer mould tool halves 7, the pressure in the gas in theupper compartment of the accumulator is used for assisting the motor inmoving the yokes 22 upwards along the vertical bars 24 against thegravitational and frictional forces.

It is desirable not to transmit the high pressure that is applied on themould tool during injection of plastic material to the frame of theinjection moulding device. Therefore, the mould tool 5, 6 is disengagedfrom the frame by means of distance cylinders 28 on the mounting part14. During opening and closing of the outer mould tool 6, when theentire mould tool package is moving downwards and upwards, the distancecylinders 28 are pressurised. When the outer mould tool 6 is closedbefore injection of the plastic material, the distance cylinders 28 aredepressurised and thus the upper part 14 a of the mounting part 14 isdisconnected from the lower part 14 b in a force transmission sense.

The supply means 23 are also provided with distance cylinders 29. Duringopening and closing of the outer mould tool 6, as the supply means 23move vertically with the outer mould tool 6, the distance cylinders 29are pressurised and thus the supply means are kept at a distance ofapproximately 0.5 mm from the outer mould tool 6 throughout the movementfor preventing scratching of surfaces of contact between the outer mouldtool halves 7 and the supply means 23. When the outer mould tool 6 isclosed before injection of plastic material, the distance cylinders 29are depressurised and the supply means 23 are free to move into contactwith the outer mould tool halves 7. Thus, plastic material may bedelivered by the supply means into the mould and forces forcing theplastic material into the mould may be transmitted.

As shown in FIGS. 9 and 10, vertical mould-locking bars 33 pass throughholes 34 in the tool holders 8. The mould-locking bars 33 are used forexerting pressure on the outer mould tool halves 7 during injection ofplastic material into the mould formed by the inner and outer mouldtools 5, 6.

Since during injection the outer mould tools 6, via the lower part 14 bof the mounting part 14, are disengaged from the frame of the device 1,the pressure added on the mould tool 5,6 is not transmitted to the frameof the device 1, but via U-shaped links 32 arranged at the top end ofthe vertical bars 24, each linking two vertical bars 24, to the baseplate 32 of the supply means 24.

With the device and method described above, it is ensured that the outermould tool halves 7 are in correct alignment when closed, so that theforming of injection moulded articles may be accurately performed. Thefact that the outer mould tool halves are kept with their central axes Ccoinciding throughout the opening and closing minimizes the risk of theouter mould tool halves being in misalignment when closed.

The skilled person will realise that a number of modifications of theembodiment of the invention described herein are possible within thescope of the invention as defined by the appended claims.

For instance, whilst in the device described above, the movement of theouter mould tool halves 6 is performed simultaneously in the first,radial direction R and the second, plane direction P, i.e. alongcircular arcs, other motion patterns are also possible. However, for thespeed of the movement it is advantageous to make the movement in thefirst and second directions at least partly coincide in time. It is alsopossible, though, to perform the movements in the first and seconddirections sequentially. The main concern is that the opening andclosing of the outer mould tool halves 7 should be quick enough not toslow down the process of producing injection moulded plastic articles.

Instead of the horizontal bars 15, the plane guide means may comprise anadditional lever arranged in parallel with each lever 9. Each additionallever is at one end pivotally attached to the mounting part 14 and atthe other end to one of the holders 8. In this manner, a parallel pairof levers 9 at each end of the holders 8 move the outer mould toolhalves 7 in the opening and closing movement. Since the distance betweenthe levers 9 in each pair is fixed, the pivoting movement of the levers9 forces the yokes 22 downwards along the vertical bars 24, moving theholders 8 and the outer mould tool halves 7 downwards in the verticaldirection R.

1. A device for forming injection moulded plastic articles, comprising apartible mould having an inner mould tool and two outer mould tools, theouter mould tools each having a central axis, the device furthercomprising a rotatable hub, the inner mould tool being supported by thehub, which is arranged to move the inner mould tool in an essentiallycircular movement into and out of a mould cavity enclosed by the outermould tools, and means for opening and closing the outer mould toolsaround the inner mould tool, characterised in that wherein the means foropening and closing the outer mould tools are arranged to move the outermould tools in a first direction which is radial in relation to the huband a second direction which is perpendicular to the first direction anddirected in the plane of the circular movement of the inner mould tool,moving the outer mould tools so that their central axes coincidethroughout the movement.
 2. A device as claimed in claim 1, wherein themeans for opening and closing the outer mould tools are arranged to movethe outer mould tools in the first and second directions at least partlysimultaneously.
 3. A device as claimed in claim 2, wherein the means foropening and closing the outer mould tools are arranged to move the outermould tools along circular arcs.
 4. A device as claimed in claim 1,wherein the means for opening and closing the outer mould tools comprisepivotable levers, each lever being articulately attached at one end toan outer mould tool and at the other end to a mounting part of a supportfor the device.
 5. A device as claimed in claim 4, wherein the positionof the mounting part is fixed.
 6. A device as claimed in claim 4,wherein the pivoting movement of the pivotable levers is driven by beltdrive means.
 7. A device as claimed in claim 1, wherein the means foropening and closing the outer mould tools comprise plane guide means forguiding the outer mould tools such that they are aligned when closed. 8.A device as claimed in claim 7, wherein the plane guide means comprisebars on which holders holding the outer mould tools are guided in thesecond direction.
 9. A device as claimed in claim 7, wherein the planeguide means are movable in relation to the mounting part.
 10. A deviceas claimed in claim 7, wherein the belt drive means are parallel withthe plane guide means.
 11. A device as claimed in claim 7, wherein theplane guide means comprise pairs of parallel pivotable levers, eachlever being articulately attached at one end to an outer mould tool andat the other end to a mounting part of a support for the device.
 12. Adevice as claimed in claim 7, further comprising radial guide means forguiding the outer mould tools in the first direction.
 13. A device asclaimed in claim 12, wherein the radial guide means are arranged toguide the plane guide means in the first direction and thereby guide theouter mould tools in the first direction.
 14. A device as claimed inclaim 13, wherein the radial guide means comprise bars on which theplane guide means are guided.
 15. A device as claimed in claim 1,further comprising supply means for supplying a plastic material to beinjected, the supply means being movable in the first direction with theouter mould tools.
 16. A device as claimed in claim 15, furthercomprising a pressure system for pressurizing the injected plasticmaterial, the pressure system additionally being arranged as anauxiliary means for closing the outer mould tools.
 17. A device asclaimed in claim 15, wherein the radial guide means additionally arearranged to guide the supply means.
 18. A device as claimed in claim 1,further comprising means for disengaging the outer mould tools from aframe of the device.
 19. A method of opening and closing a partiblemould in an injection moulding device, the mould comprising an innermould tool and two outer mould tools, each outer mould tool having acentral axis, the device further comprising a rotatable hub, the innermould tool being supported by the hub, characterised in that the methodcomprising moving the outer mould tools are moved in a first directionwhich is radial in relation to the hub and a second direction which isperpendicular to the first direction and directed in the plane of thecircular movement of the inner mould tool, with the outer mould toolsare moved so that their central axes coincide throughout the movement.20. A method as claimed in claim 19, wherein the outer mould tools aremoved in the first and second directions at least partly simultaneously.21. A method as claimed in claim 20, wherein the outer mould tools aremoved along circular arcs.
 22. A method as claimed in claim 19, whereinthe outer mould tools are guided on plane guide means in the seconddirection such that they are aligned when closed
 23. A method as claimedin claim 22, wherein the plane guide means are guided on radial guidemeans in the first direction, whereby the outer mould tools are guidedin the first direction.
 24. A method as claimed in claim 23, whereinsupply means for supplying a plastic material to be injected into thepartible mould are moved in the first direction with the outer mouldtools.
 25. A method as claimed in claim 19, wherein the outer mouldtools are disengaged from a frame of the injection moulding deviceduring injection of the plastic material.